The present invention relates to a regulating device for regulating the flow of molten metal from a metallurgical vessel wherein the device comprises a fixed tubular inner part defining at least one through-hole, and a movable tubular outer part extending around the tubular inner part and rotatable and/or slidable between a closed position, at which the tubular outer part covers the at least one through-hole to prevent molten metal from flowing from a metallurgical vessel through the at least one through-hole, and an open position at which molten metal may flow through the at least one through-hole and out of the metallurgical vessel.
Such regulating devices include the one disclosed in DE-PS 35 40 202, and are characterized in that the tubular outer part also defines a through-hole which is aligned exactly and substantially with the through-hole hole of the tubular inner part when at the open position, and is substantially out of alignment with the through-hole of the tubular inner part when at the closed position.
When the vessel is filled with molten metal, the tubular outer part is disposed at the closed position. The temperature of the tubular inner and outer parts, even if such parts are pre-heated, can initially be lower than the temperature of the molten metal in the metallurgical vessel. Test have shown that the molten metal can harden in the through-holes of the tubular outer part so as to form plugs, which plugs jam the through-holes of the tubular outer part tightly. These plugs are, on the one hand, enclosed by the edge of the comparatively cold and slightly thermally conductive tubular outer part which defines the through-hole, and, on the other hand are bordered by the tubular inner part which is also slightly thermally conductive and comparatively cold. The plugs are exposed to the hot molten metal only at one side (the outer side) thereof. Apparently, such a nearly entire enclosure of the plugs contributes to the fact that these plugs dissolve only after a long period of time, which fact has been confirmed by testing. As long as the plugs exist, it is not possible to discharge molten metal from the metallurgical vessel. The plugs in the through-holes of the tubular outer part do not dissolve, even when the tubular outer part is moved, since the plugs are encircled by that portion of the tubular outer part which defines the through-holes. In other words, the plugs move with the movement of the tubular outer part.
A similar regulating device is disclosed in DE-OS 37 31 600. The regulating device disclosed in this reference comprises a tubular outer part which is fixed to the metallurgical vessel, and a tubular inner part which can be moved relative to the outer part. Plugs can be formed in the above-described manner in the through-holes of the tubular outer part. Thus, the prior art disclosed in DE-OS 3 31 600 is subjected to the problem discussed above.